Seventeen Comprehensive Cancer Centers have now been designated by the National Cancer Institute as meeting the criteria of a Comprehensive Cancer Center Program. Four of these Programs are comprised of two or more institutions, i.e., Comprehensive Cancer Center Programs in Chicago, Denver, Philadelphia and Washington. Guidelines have been developed outlining the expected role and functions of the Epi-Stat Unit of Comprehensive Cancer Centers so as to aid the Center Directors in fulfilling the mission of the National Cancer Center Act, carry out the intended mandate of Congress and assist in developing a cancer center which is consistent with the characteristics described by the National Cancer Advisory Board. These guidelines cover the following major functions: 1) planning evaluation studies of the cancer center's accomplishments; 2) coordination of cancer epidemiologic, statistical and computer resources; 3) interpretation of trend patterns of cancer in the population served by the center; 4) education and technical assistance in theory and methodology; 5) research and disciplinary development; and 6) development of the administrative locus and organization of the unit.